Down Syndrome
Down syndrome is a chromosomal disorder when a person is born with three, rather than two, copies of the 21st chromosome. It happens in approximately 1 in 700 live births in Canada.
Normally there are 46 chromosomes (23 pairs), half of which are inherited from each parent. A person with Down syndrome, however, has cells that usually contain not 46, but 47 chromosomes, the extra one being a third chromosome 21. It is this extra genetic material that disrupts the child’s physical and cognitive development.
How is Down Syndrome Diagnosed?
Physicians may make a preliminary diagnosis of Down syndrome after careful examination of a newborn. Some common characteristics include
- Low muscle tone
- Low nasal bridge, small nose and ears
- Eye openings slanted upwards
- A ring of white dots in the iris of the eye
- Single deep crease across the center of the palm
- Excessive ability to extend the joints
- Fifth finger has one bending joint instead of two
- Small skin folds on the inner corners of the eyes
A blood test is necessary to verify the diagnosis.
Early Intervention
Children with down syndrome continue to acquire physical and mental skills throughout their lives, even though their ability levels vary considerably. In general, the average rate of progress will be slower than the general population. Among the differences noted are delays in motor skills, language skills, and social adaptability and self-help skills.
Early intervention is important in facilitating learning for children with Down syndrome as in any other children. When given equal opportunities in every stage of their lives, people with Down syndrome will make a valuable contribution to society.
Prevention and Prenatal Testing
Although there is no way to prevent Down syndrome, the risk increases with a mother’s age, or a history of genetic defects in a family. For women over 35, the risk of having a child with Down syndrome is significantly increased to 1 in 350. At age 40 the risk increases to 1 in 100 births, and at age 45 the risk becomes approximately 1 in 25.
Genetic counselling, prenatal screening and diagnostic tests are important to assess the risk of the Down syndrome.
唐氏綜合症是一種染色體病症，當一個人出生時具有三條而不是兩條21號染色體。在加拿大約700個兒童中會有一個。
通常有46條染色體（23對），其中一半是從父及母遺傳的。然而，患有唐氏綜合症的人的細胞通常不含有46條，而是47條染色體，額外的染色體是21號染色體的第三條染色體。這是額外的遺傳物質，破壞了孩子的身體和認知發育。
唐氏綜合症如何診斷？
在仔細檢查新生兒後，醫生可能會對唐氏綜合症做出初步診斷。一些特徵包括
低肌肉張力
低鼻樑，小鼻子和耳朵
眼睛向上傾斜
眼睛虹膜中的一圈白色圓點
手掌中央單一的掌紋
延伸關節的能力過大
第五根手指只有一個彎曲關節而不是兩個
眼睛內角小皮膚皺褶
驗血是必要的驗證診斷。
早期干預
儘管他們的能力水平差異很大，但患有癱瘓綜合徵的兒童在他們的一生中仍然具有身體和心理技能。一般來說，平均進展速度將比一般人慢。指出的差異包括運動技能，語言技能，社交適應性和自浬技能的延遲。
早期干預對促進患有唐氏綜合症的兒童的學習非常重要，就像任何其他兒童一樣。當他們在生活的每個階段都有平等的機會時，唐氏綜合症患者將為社會作出寶貴的貢獻。
預防和產前檢查
儘管沒有辦法預防唐氏綜合症，但風險會隨著母親的年齡增加或家族遺傳缺陷史而增加。對於35歲以上的女性，患有唐氏綜合症的患兒的風險顯著增加至1/350。40歲時，風險增加到1/100，45歲時風險約為25/1。
遺傳諮詢，產前篩查和診斷測試對於評估唐氏綜合徵的風險很重要。